title: Mammal disparity decreases during the Cretaceous angiosperm radiation.
abstract: Fossil discoveries over the past 30 years have radically transformed traditional views of Mesozoic mammal evolution. In addition, recent research provides a more detailed account of the Cretaceous diversification of flowering plants. Here, we examine patterns of morphological disparity and functional morphology associated with diet in early mammals. Two analyses were performed: (i) an examination of diversity based on functional dental type rather than higher-level taxonomy, and (ii) a morphometric analysis of jaws, which made use of modern analogues, to assess changes in mammalian morphological and dietary disparity. Results demonstrate a decline in diversity of molar types during the mid-Cretaceous as abundances of triconodonts, symmetrodonts, docodonts and eupantotherians diminished. Multituberculates experience a turnover in functional molar types during the mid-Cretaceous and a shift towards plant-dominated diets during the late Late Cretaceous. Although therians undergo a taxonomic expansion coinciding with the angiosperm radiation, they display small body sizes and a low level of morphological disparity, suggesting an evolutionary shift favouring small insectivores. It is concluded that during the mid-Cretaceous, the period of rapid angiosperm radiation, mammals experienced both a decrease in morphological disparity and a functional shift in dietary morphology that were probably related to changing ecosystems.
authors.affiliation: Department of Geological Sciences, Indiana University, , Bloomington, IN 47405, USA, Departments of Geological Sciences, Biology, and Anthropology, Indiana University, , Bloomington, IN 47405, USA.
authors.forename: David M
authors.initials: DM
authors.lastname: Grossnickle
authors.forename: P David
authors.initials: PD
authors.lastname: Polly
mesh_terms: D000818:Animals; D044822:Biodiversity; D005075:Biological Evolution; D001699:Biometry; D049628:Body Size / Q000502:physiology; D001837:Body Weights and Measures; D005580:Fossils; D007568:Jaw / Q000033:anatomy & histology*; D019684:Magnoliopsida; D008322:Mammals / Q000033:anatomy & histology*; D013045:Species Specificity; D014070:Tooth / Q000033:anatomy & histology*
keywords: Mesozoic mammals; angiosperms; functional morphology; geometric morphometrics; mandibles; morphological disparity